The present invention relates to vacuum packaging technology and, more particularly, to maximizing the cycle rate of a vacuum packaging machine.
Vacuum packaging entails the employment of negative pressure within an air tight container filled with product. The utilization of vacuum packaging technology has increased dramatically in recent years, particularly in the food packaging industry.
A typical vacuum packaging machine utilizes a modular system including the following work stations: a container forming station; a product filling station; a sealing station; and a container separating station. In operation, a lower film web is supplied to the container forming station where it is formed into a unit of containers. The containers are transported by a conveyor to the product filling station where product is added. The product-filled containers are then conveyed to the sealing station where vacuum and heat are applied to seal an upper film web to the unit of containers. The sealed containers are then transported to the separation station where the individual containers are severed from the unit.
As with any production system, it is important that the vacuum packaging system operate at the highest possible rate to promote efficiency and, hence, profitability. Conventional wisdom would dictate that in order to maximize the production rate of a modular system one would simply increase the operation rate of its constituent stations. However, because it is essential to allow sufficient time for the evacuation phase of the vacuum packaging system, it is not possible to merely increase the overall rate of conveyance through the packaging equipment to affect maximum production.
In most instances, and particularly with food products, air bubbles may be entrained within product or trapped between pieces of product in the container. An accelerated evacuation of air from the container does not adequately remove this entrained air. Improperly accelerated evacuation results in at least three problems: First, the residual air within the container causes the product to expand during evacuation. If this expansion is not restricted, the product may expand and overflow onto the sealing regions of the container thereby causing seal failures. Seal failures can result in product contamination which can be potentially harmful to the consumer. Second, the failure to remove this residual air results in increased moisture within the container. The increased moisture promotes a cooling effect during evacuation and inhibits the hermetic seal of the container also contributing to seal failure. Third, the presence of entrained air within the product increases the likelihood of contamination of the product due to the presence of derelict bacteria and fomites in ambient air. To ensure against the occurrence of entrained air within the product, it is crucial that the evacuation phase of the vacuum packaging system be gradually performed over a relatively substantial period of time.
Thus, there exists a quandary in the vacuum packaging industry between, on one hand, maximizing the cycle rate of the vacuum packaging system and ensuring sufficient evacuation and a proper vacuum seal, on the other. The present invention addresses this dilemma and resolves it.
It is therefore an object of the present invention to provide a process and apparatus which maximizes the cycle rate of a vacuum packaging system without compromising the proper evacuation and seal of the container.
It is also an object of the present invention to provide a vacuum packaging machine which can operate at an accelerated rate without increasing the likelihood of contamination of the product within the container.
It is still another object of the present invention to provide a process and apparatus for accelerating the operation rate of a vacuum packaging machine without incurring a proportional increase in operating costs.
The above and other objects of the invention will impart the obvious and will be hereinafter more fully pointed out in connection with the detailed description of the accompanying drawings.